Now the puzzle is easily solved if we apply the "non-unique rectangle" appearing in r46c69. Clearly neither "4" nor "8" can appear at r4c6, and when we eliminate those two values the {5, 6} pair is revealed -- the rest of the puzzle can be resolved by using "simple coloring" to find a few naked pairs.

What if we don't make the uniqueness assumption? Well, the solution is quite a bit more difficult, but a handful of "DIC"s will get us through it.